1. Field of Invention
The present invention relates to metal-air fuel cell battery (FCB) systems designed to produce electrical power from metal-fuel tape transported over a plurality of moving cathode structures in order to increase the volumetric power density characteristics of the system.
2. Brief Description of the Prior Art
In copending U.S. application Ser. No. 08/944,507 entitled xe2x80x9cHigh-Power Density Metal-Air Fuel Cell Battery Systemxe2x80x9d, Applicants disclose several types of novel metal-air fuel cell battery (FCB) systems. During power generation, metal-fuel tape is transported over a stationary cathode structure in the presence of an ionically-conductive medium, such as an electrolyte-impregnated gel applied to the surface of the cathode or metal-fuel tape. In accordance with well known principles of electro-chemistry, the transported metal-fuel tape is oxidized as electrical power is produced from the system.
FCB power generation systems of the type disclosed in U.S. application Ser. No. 08/944,507 have numerous advantages over prior art electro-chemical power generation devices including, for example, the generation of electrical power over a range of output voltage levels selectable to particular electrical load conditions. Also, oxidized metal-fuel tape can be reconditioned (i.e. recharged) during battery charging cycles carried out during electrical power generation, as well as separately therefrom.
However, when using such prior art technology it has been very difficult to produce FCB systems having high volumetric power density characteristics measured, for example, in kilowatts/cm3. Consequently, it has not been possible to generate large amounts of electrical power from prior art FCB systems occupying relatively small volumes of physical space.
Thus, there is a great need in the art for an improved metal-air fuel cell battery system which avoids the shortcomings and drawbacks of prior art systems and methodologies.
Accordingly, it is a primary object of the present invention to provide an improved metal-air fuel cell battery (FCB) system which avoids the shortcomings and drawbacks of prior art systems and methodologies.
Another object of the present invention is to provide a FCB system having improved volumetric power density (VPD) characteristics while avoiding the shortcomings and drawbacks of prior art systems and methodologies.
Another object of the present invention, is to provide such a FCB system, wherein metal-fuel tape is transported over a plurality of moving cathode structures during system operation.
Another object of the present invention, is to provide such a FCB system, wherein the metal-fuel tape, ionically-conducting medium and cathode structures are moved at substantially the same velocity at points where the ionically-conducting medium contacts the cathode structures and the metal-fuel tape during discharging and recharging operations, thereby minimizing the generation of frictional (e.g. shear) forces among the cathode structures, ionically-conducting medium and metal-fuel tape in the system, and thus reduce the amount of electrical power required to drive the tape transport mechanism, the shedding of metal-oxide particles from metal-fuel tape which can become embedded within the cathode structures, and the likelihood of damage or destruction of the cathode structures and metal-fuel tape.
Another object of the present invention is to provide such a system, wherein velocity synchronization of the metal-fuel tape, cathode structures and ionically-conductive medium is realizable in a variety of ways.
Another object of the present invention is to provide such a system, wherein each moving cathode structure is realized as a cylindrically-shaped rotational structure having ultra-fine perforations formed in the surface thereof and a hollow air-flow passageway extending from one end thereof to the other end thereof in order to permit oxygen transport to the interface between the ionically-conducting medium and metal-fuel tape during system operation.
Another object of the present invention is to provide such a system, wherein each rotating cylindrical cathode comprises a plastic hollow cylinder about which is attached is a cathode element made from nickel mesh sponge fabric embedded within carbon and catalyst material.
Another object of the present invention is to provide such a system, wherein during power generation operations, each cylindrical cathode structure is rotated at a controlled angular velocity, and a continuous supply of metal-fuel tape is transported over the surface of the rotating cathode cylinders at a velocity, at which the metal-fuel tape, ionically-conducting medium and cathode cylinders move at substantially the same velocity at the points (i.e locus) of contact thereamong in the system.
Another object of the present invention is to provide such a system, wherein the ionically-conducting medium is realized in the form of an ionically-conducting belt that runs over each rotating cathode cylinder in the system, between the cathode surface and metal-fuel tape transported thereover.
Another object of the present invention is to provide such a system, wherein the ionically-conducting belt is made from an open-cell plastic material impregnated with ionically-conducting material capable of supporting ionic transport between the moving cathode and anode (metal-fuel) structures in the system.
Another object of the present invention is to provide such a system, wherein the ionically-conducting medium is realized in the form of a solid-state-film applied to the outer surface of each rotating cathode cylinder, and the metal-fuel tape is realized in the form of zinc-fuel tape realized as a thin strip of zinc, or zinc power mixed with an binder and carried on a polyester substrate, or zinc powder impregnated within a substrate.
Another object of the present invention is to provide such a system, wherein each cathode structure is realized as a rotating cathode cylinder having ultrafine perforations formed in the surface thereof and a hollow central core which enables the transport of oxygen to the interface between the ionically-conductive medium and metal-fuel tape.
Another object of the present invention is to provide such a system, wherein each cylindrical cathode comprises a plastic hollow cylinder about which is attached is a cathode element made from nickel mesh fabric (for current collection) embedded within carbon, catalytic and binder material.
Another object of the present invention is to provide such a system, wherein each cylindrical cathode is rotated at a controlled angular velocity and the metal-fuel tape is transported over the surface of the rotating cathode so that both the metal-fuel tape and the cathode structure move at substantially the same velocity at the locus of points at which the ionically-conducing medium contacts both the metal-fuel tape and the cathode structure.
Another object of the present invention is to provide such a system, wherein the ionically-conductive medium is realized in the form of an ionically-conductive belt, transported (i.e. running) between two or more transport cylinders.
Another object of the present invention is to provide such a system, wherein the ionically-conductive belt is fabricated from an open-cell plastic material impregnated with an ionically-conductive material which enables ionic transport between the moving cathode and anode structures in the system.
Another object of the present invention is to provide such a system, wherein velocity control can be achieved in a variety of ways, for example: by driving each cylindrical cathode with the gears of a neighboring cathode cylinder; by driving each cylindrical cathode structure with a belt that is also used to transport the metal-fuel tape (i.e. between supply and take-up reels or hubs within a cassette type-device); by driving each cylindrical cathode structure and supply and take-up hubs of a fuel cassette device using a set of synchronously controlled motors.
Another object of the present invention is to provide such a system, wherein the ionically-conductive medium is realized as a solid-state film applied on the outer surface of the cylindrical cathode structure, and the metal-fuel tape is realized in the form of thin zinc tape, zinc power mixed with an binder and carried on a polyester substrate, or zinc powder impregnated within the substrate of the tape itself.
Another object of the present invention is to provide a metal-air fuel cell battery system, wherein each rotatable cathode structure is realized as a cathode belt structure having ultrafine perforations in the surface thereof and a hollow central core for enabling oxygen transport to the interface between the ionically-conductive medium and the metal-fuel tape.
Another object of the present invention is to provide such a system, wherein each cathode belt structure comprises an open-cell type plastic substrate, within which nickel mesh fabric or like material is embedded within carbon and catalytic material.
Another object of the present invention is to provide such a system, wherein during system operation, each cathode belt structure is transported at a controlled velocity between two or more transport cylinders, while metal-fuel tape is transported over the surface of the cathode belt structure at substantially the same velocity at the locus of points at which the ionically-conducing medium contacts both the metal-fuel tape and the cathode structure.
Another object of the present invention is to provide such a system, wherein the ionically-conductive medium of the system is realized in the form of an ionically-conductive belt structure transported between metal-fuel tape and each cathode belt structure at substantially the same velocity as the cathode belt structure and metal-fuel tape at the locus of points at which the ionically-conductive medium contacts both the metal-fuel tape and the cathode belt structure.
Another object of the present invention is to provide such a system, wherein the ionically-conductive medium of the system is realized in the form of a solid-state film integrated with the outer surface of the cathode belt structure so as to establish contact with the anodic metal-fuel tape transported thereover.
Another object of the present invention is to provide such a system, wherein the metal-fuel tape is realized in the form of thin zinc tape, zinc power mixed with a binder and carried on a polyester substrate, or zinc powder impregnated within the substrate itself.
Another object of the present invention is to provide a system, wherein the metal-fuel tape, cathode structures and ionically-conductive medium are moved relative to each other so that frictional (e.g. shear) forces generated among the metal-fuel tape ionically-conductive medium and cathode structures are substantially reduced.
Another object of the present invention is to provide a metal-air FCB system, wherein a condition of hydrostatic drag is maintained between the metal-fuel tape and the ionically-conductive medium (e.g. belt or layer) as well as between the cathode structure (e.g. cylinder or belt) and the ionically-conductive medium (i.e. belt or layer) so that all three of these moving system components can be moved at substantially the same velocity (at points where the ionically-conductive medium contacts the metal-fuel tape and the cathode structure) when only one or more of these moving system components are actively transported or rotated using a motor driven by mechanical (e.g. spring-wound), electrical, or pneumatic forces.
These and other Objects Of The Present Invention will become apparent hereinafter and in the Claims To Invention.